Laser range finders operating on pulse propagation generally do not take into consideration the inaccuracies caused by non-linearity of phase modulation of the spike or sampling pulse, derived from the transmitted pulse and which scans the received diode signals with a defined time delay. Failure to correct for the non-linearity leads to difficulties if it is desired to measure distances very accurately, for example, with errors less than one percent. In particular, the non-linearity also introduces an error in the time access of the signal pulse transformed into the low-frequency region.